The following abbreviations are defined as follows.
3GPP 3rd Generation Partnership Project
ACK acknowledged
CN core network
CRNC controlling RNC
CQI channel quality indicator
DCH dedicated channel
DL downlink
E-DCH enhanced UL DCH
DPCCH dedicated physical control channel
DRNC drifting RNC
F-DPCH fractional DPCH
FDD frequency division duplex
HARQ hybrid automatic repeat request
HS—high speed
IE information element
NACK not acknowledged
NBAP Node B application part
Node B base station
PDSCH physical downlink shared channel
RAN radio access network
RNC radio network controller
RNSAP radio network subsystem application part
SCCH shared control channel
SIR signal-to-interference ratio
SRNC serving RNC
TGL transmission gap length
TGPL transmission gap pattern length
TPC transmit power control
TTI transmission time interval
UE user equipment
UL uplink
VoIP voice over internet protocol
WCDMA wideband code divisional multiple access
Of particular interest to the exemplary embodiments of the invention described below is 3GPP WCDMA radio access, more specifically an aspect thereof proposed in 3GPP TR 25.903 V1.0.0 (2006-05), “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Continuous Connectivity for Packet Data Users; (Release 7),” at least in Section 4.2.
Section 4.2 of this document, entitled “Uplink DPCCH Gating”, describes the concept as applying to a HSDPA/HSUPA scenario only, with no DCHs configured in either direction. The uplink TPC commands sent in the downlink are assumed to be carried over F-DPCH, but one could use the associated DPCCH as well.
With regard to the general principle, it is said that the optimal solution for reducing DPCCH overhead of packet data users is turning off the DPCCH transmission when no data or HS-DPCCH is being transmitted. With such an ideal solution the idle packet data users would not consume any uplink air interface resources and the network resource allocation would set the limit on how many idle users could be kept in the CELL_DCH state. However, due to practical reasons there may be a limit on the length of the DPCCH gating period, as during a period of long UE inactivity the Node B would not know whether the uplink UE synchronization was lost, or if there is just a long inactivity period.
The basic principle is that if there is neither an E-DCH or HS-DPCCH transmission, the UE automatically stops the continuous DPCCH transmission and instead applies a known DPCCH activity (DPCCH on/off) pattern (i.e., a gating pattern). When an E-DCH or HS-DPCCH transmission takes place the DPCCH is also transmitted regardless of the activity pattern.
That is, during a period of E-DCH and HS-DPCCH inactivity the UE would activate a known DPCCH transmission pattern (i.e., a gating pattern), such as a few DPCCH slots transmitted every few radio frames, and no DPCCH transmission is made during other times. If E-DCH or HS-DPCCH is transmitted the DPCCH would be transmitted normally regardless of the pattern. Depending on the length of the DPCCH transmission gap, a DPCCH power control preamble of a few slots may be needed before E-DCH/HS-DPCCH transmission may start. Reception of the downlink HS-SCCH/HS-PDSCH would be active and possible at all times for the UE. During the periods when the UL DPCCH is not transmitted, the Node B will not be able to perform UL SIR estimation, and thus has no information on which to base the UL TPC commands sent on F-DPCH. Therefore, the F-DPCH should also be gated during the periods of UL DPCCH gating.
The above-described operations illustrate what may generally be referred to as gating and, in particular, uplink gating (i.e., gating of one or more uplink signals) in accordance with a gating pattern.
With regard to a basic packet traffic example, Figure 4.2.1.2-1 of 3GPP TR 25.903, shown herein as FIG. 1A, depicts the basic concept, where during data traffic activity (e.g., a web page is being transmitted in the downlink and TCP acknowledgments, as well as HSDPA acknowledgments are transmitted in the uplink) operation is in accordance with Release 6 specifications. When the data traffic stops, the continuous DPCCH transmission in the uplink is shut down as well. Occasionally during the period of data inactivity the DPCCH is transmitted in a predetermined pattern so that the Node B always knows to expect some slots of DPCCH transmission, and can thus still follow the uplink UE presence and quality.
Whenever the uplink has something to transmit on the E-DCH or the HS-DPCCH the DPCCH transmission will be automatically reinitiated.
More generally, during any packet session with any packet activity/inactivity ratio, when the user is transmitting data in the uplink, the DPCCH is continuously active as long as the data or HS-DPCCH transmission is taking place and, during the ‘reading time’, when the uplink is inactive, the DPCCH gating pattern would be applied, thereby reducing the consumed uplink capacity to a fraction of that required if a continuous DPCCH were used. In addition, due to the reduced uplink capacity consumption the UE talk times would be increased because of the reduced battery consumption. The actual savings would be heavily dependent on the activity factor of the uplink transmission, as well as on the amount of time allowed before dropping inactive users from the CELL_DCH.
With VoIP it would also be possible to benefit from the fact that the data transmission timing, even during the active phase of VoIP, would be known and could be matched with the DPCCH gating period. During the active speech phase the UE would transmit the VoIP packet transmissions and retransmissions with DPCCH, and between the packets DPCCH would not be transmitted.
Figure 4.2.1.3-1 of 3GPP TR 25.903, shown herein as FIG. 1B, illustrates an exemplary DPCCH transmission with gating, a 2 ms E-DCH TTI and VoIP traffic (with an average transmission rate of 2.5 transmission per packet) mapped to HARQ processes 1 and 2. Also shown is the DPCCH activity pattern during E-DCH inactivity as a 2 ms burst every 32 ms. Note that this is a simplified example, and that the transmissions and retransmissions do not need to follow this regular pattern in order to obtain the desired benefits from the DPCCH gating. With such parameterization the DPCCH overhead would be reduced to ˜6% during voice inactivity and to ˜25% during voice activity. Assuming 50% voice activity the DPCCH overhead would be reduced to ˜16% of the overhead from continuous DPCCH. HS-DPCCH activity and possible power control preambles would reduce the actual gains, but with good parameterization and possible improvements to CQI reporting, the impact of HS-DPCCH is not dominant.
Figure 4.2.1.3-2 3GPP TR 25.903, shown herein as FIG. 1C, illustrates an exemplary DPCCH transmission with gating and 10 ms E-DCH TTI, and VoIP traffic (no retransmissions shown, low retransmission rate) mapped to HARQ processes 1 and 3. Also shown is the DPCCH activity pattern during E-DCH inactivity as a 2 ms burst every 20 ms. With such parameterization the DPCCH overhead would be reduced to 10% during voice inactivity and to ˜50% during voice activity. Assuming 50% voice activity the DPCCH overhead would be reduced to ˜30% of the overhead from continuous DPCCH. HS-DPCCH activity and potential power control preambles would reduce the actual gains.
With regard to the operation of the uplink DPCCH gating, the RNC would control the activation and deactivation of the Uplink DPCCH Gating feature in the same manner that the RNC controls the Preamble/Postamble transmission for HSDPA ACK/NACK transmission. This is said in 3GPP TR 25.903 to be essential in order to guarantee the functionality in the SHO, as gating can be used only if all Node B's in the active set support it. The RNC should also decide what kind of gating parameters would be used, and signal the information to the Node B(s) and UE. If a Node B in the UE's active set does not support gating the RNC must disable the Uplink DPCCH Gating.
When the Uplink DPCCH Gating feature is enabled by the RNC the UE would transmit the DPCCH continuously when E-DCH or HS-DPCCH is transmitted, and transmit the DPCCH discontinuously during the inactivity of E-DCH and HS-DPCCH according to parameters provided by the RNC.
Additional 3GPP specifications of interest include 3GPP TS 25.423 and 25.433, more specifically: 3GPP TS 25.423 V6.8.0 (2005-12), “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; UTRAN Iur interface RNSAP signalling (Release 6),” and 3GPP TS 25.433 V6.8.0 (2005-12), “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; UTRAN Iub interface Node B Application Part (NBAP) signalling (Release 6).”
As of the filing date of the above-cited provisional application from which priority is claimed, the most recent versions of these two 3GPP specifications are: 3GPP TS 25.423 V6.10.0 (2006-06), “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; UTRAN Iur interface Radio Network Subsystem Application Part (RNSAP) signalling (Release 6),” and 3GPP TS 25.433 V6.10.0 (2006-06), “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; UTRAN Iub interface Node B Application Part (NBAP) signalling (Release 6).”
The inventors have realized that the execution of the uplink DPCCH Gating feature as described above in reference to 3GPP TR 25.903 is not possible with the Iub/Iur signaling as defined in accordance with the current 3GPP specifications.